Steel wool machine



March 9, 1948. GALVlN STEEL WOOL MACHINE 4 Sheets-Sheet.- 1

Filed Jan. 21, 1943 llr INVENTOR GEORGE B.GALVIN.

ATTORNEYS March 9, G B, GALVlN STEEL WOOL MACHINE Filed Jan. 21, 1943 W M Q m Q1 mm i A w .w V

ATTORNEYS Ma h' 9; 1948. I 15. GALVIN 2,437,424

STEEL WOOL MACHINE Filed Jan. 21, 1943 4 Sheets-Sheet 3 INVENTOR GEORGE B. eALvm, BY

ATTORNEYS I March 9, 1948. G N 2,437,424

STEEL WOOL MACHINE Filed Jan'. 21, 1-943 4 Sheets-Sheet! INVENTOR GEORGE B.GALVIN,

MM ATTORNEY-5 Patented Mar.v 9, 1948 UNITED STATES PAT Q FFLCE;

2 .431.424 STEEL WOOL George -B Galvin, Springfleldg Ohio ApplieatiomJanuary 21, 1943, Serial No. 473;}31;

This invention r. =.1atestogmachinesfor prodncing metal wool.

An object of the invention is; to; provide. an.

improved metal woolproducing machinewhfiliein the tension on the. wire-being out isreduced to a minimum.

wire passes beneath a; plurality, otcutting; tools by passing. through. the; machine. many timesso that. the: wire. is: out down rtq its minimum; size before being removed from the machine, and wherein the wire. is; independently driveneachtime it passes; beneath. a: predetermined; number of cutting tools. 7

Another object. at the; invention is to; provide a metal wool-produeingemaehine;wherein a single; wire is passed through thqmachine, and in its passage. through. the machine; forms: aplurality. of loops that are independently driven so; that eaclr loopof. the; wire is; only requiredtc, have; tension. thereon of sufiicient quantityto draw it past a selected number of cutting tools, whereby the tension'on the wire can;begovernedraecording to the tension oapable of 'being abserbed; by;- thesmallest diameter wire and; therebypreventing,

breakage. of the, wire; in; the. machine:

It is another objectrofthe-inventign to; previde;

ametal wool forming; machinewherein all-.of the.- cutting takes placeonz-QILQ side ofgthewira. and}. on one side of: the-machine; and at rotatahledrnm is provided: for feeding the-wirethrough the machine so that the; tension. on; each loop: f wi passing through;themaflhine-is the same and'cant be gcv emed by the-minimum. tensipnthgt; b absorbed: by the smallesiisize-wireiwithout, break;- age.

It is another object. oiithe invention-to provide a metal wool forming machinewheneini asingle' wire in. passing through the machine: forms:.,a: plurality of loops; so; that'- the' wire; can. be: worked? upon a: number of: times; by: a; single:- eutting tool", the cutting: tool being constructed. and: arranged": so that it will remove approximately, the same: amount of: wool from theawireseach time thewire passesheneath thacuttihgtool'l.

Another object ofi-theinventionais to provide a new and improved cutting tool.- and holder for the tool for metalwczolforming'n achine.

Another object of the invention-is to: provide: a new and. improved. cutting. tool: for a; metal wool;

' cutting tools are, positioned'npon asingle bed in.-

forming. machinewherein the hqlderisad ustable in three: e ent: planes. to prev/ride complete. angular adjustment oi the. cutting teol.

Another objectoi the inventionis; tapnovide a,

a o a ms. (01.29.114.51

metalfwooliforming, machine wherein all of the.

the machine so. that, all; of the cuts, made. upon. the wire; areproducedonone side of themachine and all. of thetool's. can. be under; the continuous.

observation of a. single. operaton.

Another object of; the invention is to provide an improved structural arrangement. of a metalwool. producing machine 1 Further objects and advantages will become apparent from. the. drawings and the. following description.

In the drawings:

F s 1 is. a. plane elevational view of the metal wool producing machine of this. invention with. the wiresupply. roll; and tfalge-uproll shown somewhat, diagrammatically.

Fig. 2. is a vertical. cross-sectional view. of the maehine takenalong line 2:4 of'Fig. 1.

Fig. 3 isa front elevatibnal view offthe machine, aportion. thereof hei'ng lirokenaway to indicate the position of the cutting tools.

Fig. 4 is a side. elevational view off'a. portion. ofthe machine showing the manner in. which a singlewire is wound. about the driving drum. and passes from one-gronpotcuttersto the next.

Fig. 5 is a crossrsectional' view taken along 5.--&

of Fig. 1 showing the pressure rolls for. preventing rotation of the wire when. passing beneath the cuttingtools of. the machine.

Fig. 6? isacross-sectional. view of a portion of the driving drum showing the grooved. surface therein for guiding. the wires-aroundthe drum.

Fig. 7' is: across-sectional. view of 'acutting tool.

engaging plurality of wiresfor removingmetal wool from each: of the wires. simultaneously.

Fig. 8 is anelevational'view of a portion of the metal wool producing. machine. showing the, cutting tool holders: in: cross-sectionto illustrate the construction thereon,

Fig. 9 is.' an end elevational view ot a. pair. of. cuttingtools. shownzmountedin their holders. and on; the.v machine. as viewed; from. the, direction of, thearrow A on 8...

Fig. 10 ;is;a= cross seetional. view taken along line. Ill-$1 0,- oi; Fig,

In-this invention the; machine... consists of a, base member H1. that; is providedwith a gear box. ll (Figure 2); positioned substantially centrally. within the base-member. 1. The base "I. has a front; ledge 12 that supports a vertical frame. l3,

which in turn supports the wirecutting unit. l5.

A rear ledge i3 is carried by the base In and supports a rear frame 26, a top frame 2| being positioned between the rear frame 23 and the front frame l3 and suitably secured thereto as with bolts 22. The-front frame I3 is secured to the ledge i2 by means of the bolts 23 and the rear frame 25 is secured to the rear ledge H! by means of the bolts 24.1 Y

The gearbox I i .is provided with a bearing box 25 that supports a vertically disposed shaft 26 by means of the thrust bearing 21. Axle bearings 28 are provided in the bearing box 25 and the cover 29 for the gear box shaft 26 is suitably bearinged in the bearing box 36 provided in the upper frame 2| by means of the anti-friction bearing member 3|.

A drive drum 32 is secured to the shaft 26 and feeds the wire through the cutting unit 15 from which the metal wool is cut. The lower end of the drive shaft 26 carriesa worm wheel 33 that is driven by a worm 34 secured upon a drive shaft 35 that is suitably bearinged in the gear box II and the bearing box 36 carried upon the rear ledge IS. A suitable electric motor. 31, or other convenient source of power is connected to the drive shaft 35 for rotating the same and thus driving the drum 32.

The front frame l3 supports a plurality of cut ting units I5, each of which, as shown in Figs. 8 and 9 consists of a'base 38 that extends throughout substantially the entire height of the front frame l3 to support a plurality of cutting tool holders 46 upon arms 4| that extend outwardly from the base 35. The frame I3 is provided with a plurality of parallel recesses 42, one of which is shown in Fig. 8, to receive the base members 38 of the cutting units which are suitably secured in these recesses. Each of the tool holders 40 is supported between a pairof the arms 4|, a pair of tool holders 45 being disposed between each pair of arms 4|. I

Each of the tool holders 40 consists of a yoke member 43 thatis' provided with a channel shape slot 44 to receive a cutting tool 45 having a cutting edge. 46. The cutting'tool 45 is secured in position in thechannel shape slot 44 by means of set screws 41..

The yoke 43 is provided with axially aligned holes 48 that receive the smooth shanks 49 of screws 50 providing. means upon which the yoke 43 can pivot. The block 5| is supported upon an eccentric53 that is carried upon the shaft 52. The eccentric 53 is provided with teeth thereon that form a worm wheel 54 that is engaged by a worm 55 provided upon a shaft 56 bearinged in the block 5|. The shaft 55; is provided with a collar 5'! that engages a sleeve 53 pressed into a bore 59 provided in the block 5| to retain the shaft 56 in the block 5|. A suitable nut 66 is provided on the shaft 56 whereby the shaft is positioned within the block 5|. When the shaft 56 is rotated the eccentric '53 will be rotated upon the shaft 52 to thereby move the block 5| toward or away from the base 38 of the cutting unit.

The shaft 52 extends throughout the length of each of the cutting unitsi5, as shown in Fig. 1, so that it supports all of the tool holders on a particular cutting unit l5. A retaining member 5| is provided with arms 62 that are adapted to co-operate With'.th arms 4| on the base 38 to retain the shaft 52 in position in the cutting unit I5, suitable screws 63 being provided to secure the retaining member 6| to the arms 4| 7 As previously mentioned the yoke 43 is pivotally mounted on the block 5| by means of the i 43about the pivot screws 56.

The upper end of theaxis parallel with the axis of the shaft 52.

screws 50. The yoke 43. can thus be moved at right angles to the axis of the shaft 52 to position the cutting tool 45 angularly to the axis of the shaft 52. To control the angular position of the yoke 43, and thus the cutting tool 45, a pair of set screws 64 are in threaded engagement with a ledge 54a on the block 5|, and engage the yoke 43 upon opposite sides of the axis of screws 56 so thatmovement of the set screws 54 inwardly or outwardly will produce rotation of the block Also, the block 5| together with the yoke 43 is rotatable on an axis coaxial with the eccentric 53, and thus upon an axis parallel with the axis of the shaft 52 so that the cutting tool 45 can be rotated about an The angular setting of the tool 45, when the block 5| is rotated axially upon the eccentric 53, is controlled by means of the thumb screws 55. It will thus be seen that the cutting tool 45 is provided with three different adjustments. The first adjustment would be the thumb screw 65 to angularly position the cutting tool relative to the base 38 so that the cutting edge 46 will be disposed at a predetermined and selected angle for removing wool from wires that pass beneath the cutting tool. The second adjustment is the pivotal adjustment of the yoke 43 upon the screws 56 so that the cutting edge 46 of the cutting tool 45 can be adjusted angularly relative to the plane of cutting so that a single wire can be cut a number of times when passing under the same tool on a plurality of passes beneath the cutting edge of the tool. The third adjustment is that accomplished by the rotation of the eccentrio 53 whereby the cutting tool 45 can be moved perpendicular to the base 38 without altering the angular adjustment obtained by movement of the set screws 64, and the angular adjustment of the thumb screws 65 can be reobtained by merely turning them a predetermined number of revolutions.

A guide plate 66 is provided beneath each pair of cutting tools 45 and extends throughout the length of the machine, as shown in Fig. l. The guide plate 66 is supported upon the front frame l3 and the base members 38 of the cutting units l5. Each guide plate 66 is provided with a plurality of parallel grooves 61 that are all of the same depth, the grooves extending throughout the length of the guide plate 66 so as to guide the wire in its path of travel beneath the cutting tool 45 when passing through the cutting units I5. In fact, each of the guide plates has two sets of grooves, one of which is disposed beneath each of the cutting tools 45 carried between a pair of arms 4|, asshown in Fig. 9. As shown in Fig. 7 each set of grooves 61 consists of a series of twelve grooves so that a wire can pass beneath each cutting tool 45 twelve times, or twelve wires can be simultaneously passed beneath the cutting tool 45. If thesame wire is passed beneath the cut- 'ting tool twelve times, as will hereinafter be described, it willbe apparent each time that it passes beneath the cutting tool that the tool must be positioned somewhat closer to the guide plate 66 in order to engage the wire. As will be noticed in Fig. '7 the serrated cutting edge 46 of the cutting tool 451s disposed angularly relatively to the plane of the surface of the guide plate 63 so that the uppermost edge 46a is closer to the guide plate 66 than the lowermost edge 46b. Therefore, each time the wire 1!) passes beneath the cutting edge 46 a quantity of metal wool will be removed from the wire. The purpose of the in Fig. 1.

adjusting screws 64 now-becomesapparent. .It-

is to produce this angular position or the cuttingtool 45? This arrangement avoids: all necessity: of precision grinding of the wire guide 66 groovesof' slightly different depth to: take care rolls H; are provided at each end of the guide plates 65', as shown in Fig. 1 each pressure rollerbeing of a sufiicient width to cover two groups of twelve wireseach, as shown in Fig. 5; Each pressure-roller I I is carried'in a slot 12 (Figure 8) provided in an arm 13 extending from the front frame l3. anda cover can Hi secured to the arm 1-3- by means of the screws L5 Adjusting screws 16- engageopposite ends of the shaft 11 of each pressure: roller H to adjust it angular-1y relative totheplane of the: guide plate 66 to: accommodate wires of varying thickness passing beneath the pressure roller H and thus prevent the wires from: rotating in thegrooves so that they will always present theoriginal flat surface to the cutting: tools- 45 after thewire has started its. travel through the machine.

Tocomplet'e the-description of thev machine, an

idler roll 18 is positioned at each end of the guid plate 66 adjacent thepressure rolls H, as shown Theseidler rolls are provided with a series of grooves therein that are arranged in groups in thesame-manner as the group of guide grooves 61in the guide plates 65 50 that a wire passing from the plate 66' will have a groove in the idler roll that cooperates therewith to guide the wire over the idler roll 7-8 The surface of the drivedrum azisalsoprovided with a plurality of" grooves: therein, 'asshown in Fig. 6, so'that the wire will be guided over the surface of the drum: 32 whileit isin engagement therewith.

A supply roll 89- having the wire It thereon is supported adjacent the machine in a suitable bearings support 8!. so that it is freely rotatable. If desired, or if necessary, a suitable brake can be provided for the supply roll fill so that it will not rotate faster than thewire can be used. there from..

A wire straighten-er 8.2-is positioned etween the supply: roll 8i) and. the metal wool producing machine to: remove all kinks and bends. Any conventional wire straightener can be'used, but as shown herein a series of rolls 83- and 8 are positioned on opposite sides of the'wire Til and a similar set of rolls 85- is positioned at right angles to the plane in which the rolls 83 and 84 are positioned whereby all kinks and bends are removed.

The single strand of wire 10 is threaded over the idler rolls and beneath the cutting tools 45 in the cutting units l5 so that the strand of wire forms a plurality of' loops that extend around the idler rolls 18' and the drive drum 32; As shown in Figs; 3' and 4, the single strand of wireis fed over the idler roll 13 on. the lowermost groove 86. The wire is then carried over the drive drum 32' in the lowermost groove in the drum and returned to thefeed ro1l'18- in the opposite end" of the machine. As previously mentioned the grooves in the-idler rolls and the drive drum arearranged ingroups of twelve each, two groups of twelvebeing: placed in alignment with, the; two groups of twelve grooves. provided the guide plate. 66,. so that. the Wire; guided to' and: from the guide plate at each end thereof. After the wire has been wound around" the idler rolls. 18: and the drive drum 32' to completely fill the first group, or lowermost group, of grooves: therein, the wire is thenpassed to the grooves associated with the sec- 0nd row of cutting tools disposed from the bot-. tom upwardly of the machine, the wire crossing between the first and second set of grooves as shown by the angular position of the wire 10a, see Fig; 4. A single strand of wire is thus wound around the idler rolls, the drivedrum and over the various guide: plates for the various rows of cuttingtoolsso that the single strand, of wire H1- finally leaves the wool-producing machine at the uppermost groove 81' provided in the idler roll 13 0b the right-hand side of the machine, as shown in Fig, 3. This single strand of wire is then carried over a receiving roll $28 that is suitably bearinged in. thebearing member 89' for rotation therein. When the strand of wire Hi leaves the machine it. has been out down to its minimum size, which is such a size that it would no longer stand? any. substantial tension tor drawing the wire past a. number of cutting tools.

The receiving: roll 88. can be. driven. in any conventional mannerso that the wire strand 10 is takenupfrom the machine just as. fast as it is fed from the machine by the; drive drum 32. The: tension on the wire strand 10 leaving the machine should be maintained substantially uni form so that it. will not break and thus cause a 'shutdown of. the machine. Suitable tension control devices can be. associated with the; Wire strand: leaving the machine to control the tensi'onthereof by regulating the speed of the receivingroli 8B.-toprevent breakage oft-he strand, or a variable speed drive mechanism can be associated with the; receiving roll 88 to. vary the speed; of rotation of thezreceiving roll inacoordance with. the quantity of wire that has, been received upon. the roll so that a substantially constant tension. will be maintained upon the more strand 1.0;.

Such a variable speedv drive has been diagrammatically illustrated for driving the receiving roll 88; and: consists or a. variable speed drive unit 90. having: sheaves. 9i and 92 that are movable axially toward and away from one another with a belt 93 extending therebetween so that when the sheaves 92 aremoved toward one another the sheaves 9|? will; be moved away. from one another whereby the speed of rotation of the outputshaftyilii oi; the. variable speed drive unit 9.0; will berreducedzx To controlthe'movement of: thez sheavess 92 ayrod. 95; may engage the surfaoewof the Wireupon, the receiving roll 88, wherebythe; rod& 95. will; be moved outwardly from thaaXiS 'ofithe; roll 88: as. the layers of. wire increasatheneon... A suitable lever seems. he operated; by the rod; 9.5 tocontrol the sheaves. t2 through a mechanism. within the variable speed dIiVf unit. 951.. Such mechanisms are wellknown. as well as. the general construction of the. variable speed drive: unit itself. Any one of the many type otunitsthat are available on the-,general; open market can be used in connection. with; this invention. A. suitable manual control: 95!; may supplement the automatic control of: thezvariableaspeed drive unit hit to rough.- ly set the output shaft: 91dbefore; the wool producing? machine. is: started. in operation;

Eromythisz. invention. it; will, be seen; that. a

single strand of wire is started into the wool producing machine at one end and is removed from the opposite end of the machine after it has been operated upon by the cutting tools of the machine 1152 times whereby the wire is reduced from its full diameter down to its minimum size before it is removed from the machine. Also, all of the cutting tools on the machine'are available for constant inspection of a single operator without moving around the machine so that in case fault should occur at one of the cutting tools it can be immediately remedied before sufficient damage occurs to cause the machine to shut down.

Since a single strand of wire is used in the machine it will be apparent that the tension of the strand must be maintained uniform throughout its entire length to prevent breakage of the strand while it passing through the machine. The driving arrangement for the strand which consists of the drive drum 32 of this invention is such that each loop of the strand of the wire 10 is individually driven and therefore only sufficient tension is required in each individual loop to draw it past the cutting tools, in a single passage across the guide plates 66. Therefore, each loop of the wire is maintained under a minimum tension which can be regulated according to the tension of the minimum diameter of the wire that is bein removed fro-m the uppermost or last groove in the top guide plate just before the wire leaves the machine. Since tension on the wire is governed by the minimum size of the wire that is leaving the machine it is quite apparent that the wire strand will not break in any other portion of the machine because it is of a larger diameter in all other portions of the machine so that if the minimum tension will not break the wire just before it leaves the machine that it will not break in any other portion of the machine.

Therefore, with the arrangement disclosed in this invention there is practically no danger of the breakage of a wire strand while passing through the wool producing machine.

While the form of the invention disclosed and described herein constitutes a preferred form, yet it is to be understood that the apparatus is capable of mechanical alteration without departing from the spirit of the invention, and that all such modifications as fall within the scope of the appended claims are intended to be included herein.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is: V

1. A cutting tool for a wool producing machine which consists of a base member, a tool holder, a support block, a support shaft for said support block, means adjustably mounting said support block on said shaft for moving the support block normal to the shaft and substantially parallel thereto, means for rotatably adjusting said support block upon said shaft, and means adjustably mounting said tool holder upon said support block for rotation at right angles to said shaft.

2. A cutting tool for a metal wool producing machine comprising a base member, a shaft supported by said base member, an eccentric rotatably supported upon said shaft, a support block carried by said eccentric and means for rotating said eccentric therein to change the position of said support block relative to the axis of said shaft, means for rotatably adjusting said support block upon said eccentric to change the angular position of said support block relative to said base member, a tool holder, pivot means normal to said shaft for mounting said tool holder upon said support block, and means for rotatably adjusting said tool holder upon said support block to change the angular relationship therebetween.

3. In a metal wool machine for a single strand of wire, a pair of idler rolls having grooves therein to independently receive a loop of a wire strand that passes through the machine, a drive drum of substantially larger diameter than said idler rolls having grooves therein for independently receiving a loop of the wire strand and positioned midway between said idler rolls with the periphery of said drum adjacent a plane extending across the periphery of said idler rolls whereby a wire strand may be threaded through the machine by passing the same over the surface of the idler rolls and said drum to arrange the Wire in a plurality of loops thereover having a substantially triangular shaped arrangement so that each loop of the wire strand will be frictionally maintained under independent tension between said idler rolls and said drive drum, the tension of each loop being equal, a stationary and fixedly mounted guide plate disposed between said idler rolls having grooves of equal depth therein aligned with the grooves in said idler rolls for guiding the loops of the wire strand between said idler rolls, pressure rolls disposed adjacent each end of said guide plate to engage the cut faces of the wire passing thereover and prevent rotation of the wire strand passing across said plate, a plurality of cutting tools disposed adjacent said guide plate for removing wool from the wire strand passing across said guide plate, said cutting tools having cutting edges of a width surficient to simultaneously engage a plurality of consecutively adjacent loops of the wire strand to simultaneously remove a substantially like quantity of wool from each of the loops engaged by the tool, means mounting said rollers so that their axes may be adjusted into parallelism with said cutting edges, means for adjustably and fixedly positioning the cutting edge of the cutting tool angularly relative to the plane of the guide plate to produce substantially uniform engagement with all of the loops of the Wire strand engaged by the tool, means for adjusting said angular position of the cutting tool to change the cutting angle thereof relative to said guide plate, and means for adjusting the cutting tool toward or away from said guide plate without altering said angular position of said cutting tool.

4. A cutting tool for a metal wool producing machine that includes in combination, a base member, a shaft supported by said base member, an eccentric rotatably supported upon said shaft, a support block bearinged upon said eccentric for rotation thereon, means carried by said support block for rotating said eccentric upon said shaft whereby to move said support block parallel to said shaft, means adjustably interconnectin said base member and said support block for rotating said support block upon said eccentric, a tool holder, pivot means normal to said shaft for pivotally mounting said tool holder on said support block, and means adjustably interconnecting said tool holder and said support block for rotating the tool holder upon the support block to change the angular relationship therebetween and maintain the same irrespective of adjustments made by the first two mentioned adjusting means.

5. In a machine for producing steel wool by simultaneously shaving consecutive, substantially coplanar passes of asingle elongated wire, said passes determining a plane, a support, a shaft carried by said support parallel to said plane, a block pivoted on said shaft, a yoke adapted to receive and hold a tool, with its cutting edge in simultaneous shaving contact with all of said passes, and means pivotally mounting said yoke on said block whereby to vary the angle between the cutting edge of said tool and said plane,

6. A metal Wool machine comprising a base, a tool support secured to said base along one edge thereof, a pair of rolls pivoted on said support on spaced parallel taxes, a frame secured to said base and to said support, a shaft j ournaled in said base and frame on an axis parallel to the axes of said rolls, a driving drum of substantially larger diameter fixed to said shaft, said drum having a portion of its periphery closely adjacent the plane of the axes of said rolls and between said rolls,

said drum and rolls having their peripheries grooved to guide a length of wire in a plurality of generally triangular loops thereabout, the loops between said rolls forming passes lying in a com-' mon plane, a plate fixed on said support having grooves of equal depth to receive the said passes so that said passes of wire slide thereover in said grooves, a tool shaft fixed to said support and said cutting edge and the plane of said passes.

7. In a machine for producing metal wool by simultaneously shaving consecutive parallel passes of a single strand of metal, said passes lying in a plane, a support, arms on said support, a shaft carried by said arms with its axis substantially parallel and closely adjacent to said plane, block means journaled on said shaft, a tool carrier pivoted on said block on an axis perpendicular to the axis of said shaft, said carrier being adapted to hold a tool with its cutting edge in simultaneous shaving contact with said passes, means to fix said block means in adjusted position about said shaft, and means to pivotally adjust said carrier with respect to said block means, to vary the angular relation of said cutting edge and said plane.

. 8. In a machine for producing metal wool, a late having parallel grooves therein of equal depth, means for moving a plurality of consecutive passes of a single length of wire in the same direction across and in contact with said plate, a cutting tool, means mounting said tool so that its cutting edge engages all of said passes to cut wool therefrom and at a, predetermined angle to said plate, presser means adjacent said edge, and means mounting said presser means for angular adjustment relatively to said plate to engage the cut faces of all passes and hold said passes against said plate with substantially equal pressure while maintaining said faces in a common plane with said edge angularly to said plate.

GEORGE B. GALVIN,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,548,807 Schonitzer Aug. 4, 1925 1,766,356 Robbins June 24, 1930 1,894,447 Robbins et al. Jan. 17, 1933 1,894,448 Robbins et al. Jan. 17, 1933 1,912,951 Robbins June 6, 1933 1,912,964 Boehler June 6, 1933 

